Well if you are making a functional blowback bolt, why not have an optional "heavy" bolt, which requres a tune that releases more gas towards blowback, inorder to keep a good firerate and have the bolt travel properly and reliably.
If this hits production, I would absolutely love to own an AK variant
Id say that making proper blowback would be more complicated on an AK vs say... an M16. Externally, the AK Bolt carrier travels much farther per shot (The M16 bolt outta travel just as much, but you can only see it partially, only as far as the ejection port shows). Not sure if thats a clear explanation, I could clear it up with some pics if that doesnt make enough sence
Cheers!
Alex